electronics fundamentals circuits, devices, and applications THOMAS L. FLOYD DAVID M. BUCHLA chapter 1

Example-1 Scientific and Engineering Notation Very large and very small numbers are represented with scientific and engineering notation. Example-1 47,000,000 = 4.7 x 107 (Scientific Notation) = 47 x 106 (Engineering Notation)

Example-2 Example-3 Scientific and Engineering Notation 0.000 027 = 2.7 x 10-5 (Scientific Notation) = 27 x 10-6 (Engineering Notation) Example-3 0.605 = 6.05 x 10-1 (Scientific Notation) = 605 x 10-3 (Engineering Notation)

Metric Conversions Numbers in scientific notation can be entered in a scientific calculator using the EE key. Most scientific calculators can be placed in a mode that will automatically convert any decimal number entered into scientific notation or engineering notation.

SI Fundamental Units Quantity Unit Symbol Length Meter m Kilogram kg Second s Ampere A Kelvin K Candela cd Mole mol Mass Time Electric current Temperature Luminous intensity Amount of substance

Some Important Electrical Units Except for current, all electrical and magnetic units are derived from the fundamental units. Current is a fundamental unit. Quantity Unit Symbol Current Ampere A Coulomb C Volt V Ohm W Watt W Charge These derived units are based on fundamental units from the meter-kilogram-second system, hence are called mks units. Voltage Resistance Power

Large Engineering Metric Prefixes P T G M k peta tera giga mega kilo 1015 1012 109 106 103 Can you name the prefixes and their meaning?

Small Engineering Metric Prefixes m n p f milli micro nano pico femto 10-3 10-6 10-9 10-12 10-15 Can you name the prefixes and their meaning?

Example-1 Metric Conversions Smaller unit 0.47 MW = 470 kW When converting from a larger unit to a smaller unit, move the decimal point to the right. Remember, a smaller unit means the number must be larger. Smaller unit Example-1 0.47 MW = 470 kW Larger number

Example-2 Metric Conversions Larger unit 10,000 pF = 0.01 mF When converting from a smaller unit to a larger unit, move the decimal point to the left. Remember, a larger unit means the number must be smaller. Larger unit Example-2 10,000 pF = 0.01 mF Smaller number

Example-1 Metric Arithmetic 10,000 W + 22 kW = When adding or subtracting numbers with a metric prefix, convert them to the same prefix first. Example-1 10,000 W + 22 kW = 10,000 W + 22,000 W = 32,000 W Alternatively, 10 kW + 22 kW = 32 kW

Example-2 Metric Arithmetic 200 mA + 1.0 mA = When adding or subtracting numbers with a metric prefix, convert them to the same prefix first. Example-2 200 mA + 1.0 mA = 200 mA + 1,000 mA = 1,200 mA Alternatively, 0.200 mA + 1.0 mA = 1.2 mA

} Error, Accuracy, and Precision Precise, but not accurate. Error Experimental uncertainty is part of all measurements. Error is the difference between the true or best accepted value and the measured value. Accuracy is an indication of the range of error in a measurement. Precision is a measure of repeatability. Error } Precise, but not accurate.

Example Significant Digits When reporting a measured value, one uncertain digit may be retained but other uncertain digits should be discarded. Normally this is the same number of digits as in the original measurement. Example Assume two measured quantities are 10.54 and 3.92. If the larger is divided by the smaller, the answer is 2.69 because the answer has the same uncertainty as the original measurement.

Significant Digits Rules for determining if a reported digit is significant are: Nonzero digits are always considered to be significant. Zeros to the left of the first nonzero digit are never significant. Zeros between nonzero digits are always significant. Zeros to the right of the decimal point for a decimal number are significant. Zeros to the left of the decimal point with a whole number may or may not be significant depending on the measurement.

Examples: 1. Nonzero digits are always considered to be significant. 2. Zeros to the left of the first nonzero digit are never significant. 3. Zeros between nonzero digits are always significant. 4. Zeros to the right of the decimal point for a decimal number are significant. 5. Zeros to the left of the decimal point with a whole number may or may not be significant depending on the measurement. Example: 23.92 has four nonzero digits – they are all significant. Example: 0.00276 has three zeros to the left of the first nonzero digit. There are only three significant digits. Example: 806 has three significant digits. Example: 9.00 has three significant digits. Example: 4000 does not have a clear number of significant digits.

Rounding numbers Rounding is the process of discarding meaningless digits. Rules for rounding are: If the digit dropped is greater than 5, increase the last retained digit by 1. If the digit dropped is less than 5, do not change the last retained digit. If the digit dropped is 5, increase the last retained digit if it makes it even, otherwise do not. This is called the "round-to-even" rule.

Utility voltages and GFIC Most laboratory equipment is connected to 120 Vrms at the outlet. Wiring to the outlets generally uses three insulated wires which are referred to as the “hot” (black or red wire), neutral (white wire), and safety ground (green wire). Neutral Hot Ground Notice that neutral is larger than the hot line. GFIC circuits can detect a difference in the hot and neutral current and trip a breaker. One outlet on the circuit will have reset and test buttons.

Electrical Safety Safety is always a concern with electrical circuits. Knowing the rules and maintaining a safe environment is everyone’s job. A few important safety suggestions are: Do not work alone, or when you are drowsy. Do not wear conductive jewelry. Know the potential hazards of the equipment you are working on; check equipment and power cords frequently. Avoid all contact with energized circuits; even low voltage circuits. Maintain a clean workspace. Know the location of power shutoff and fire extinguishers. Don’t have food or drinks in the laboratory or work area.

Key Terms Engineering notation Exponent Metric prefix Power of ten A system for representing any number as a one-, two-, or three-digit number times a power of ten with an exponent that is a multiple of three. The number to which a base is raised. A symbol that is used to replace the power of ten in numbers expressed in scientific or engineering notation. A numerical representation consisting of a base of 10 and an exponent; the number 10 raised to a power.

Key Terms Scientific notation Accuracy Precision Significant digit A system for representing any number as a number between 1 and 10 times a power of ten. An indication of the range of error in a measurement. A measure of the repeatability (consistency) of a series of measurements. A digit known to be correct in a number.

Quiz 1. A number written as 2.59 x 107 is said to be in a. scientific notation b. engineering notation c. both of the above d. none of the above

Quiz 2. The electrical unit that is fundamental is the a. volt b. ohm c. coulomb d. ampere

Quiz 3. In scientific notation, the number 0.000 56 is written a. 5.6 x 104 b. 5.6 x 10-4 c. 56 x 10-5 d. 560 x 10-6

Quiz 4. In engineering notation, the number 0.000 56 is written a. 5.6 x 104 b. 5.6 x 10-4 c. 56 x 10-5 d. 560 x 10-6

Quiz 5. The metric prefix nano means a. 10-3 b. 10-6 c. 10-9 d. 10-12

Quiz 6. The metric prefix pico means a. 10-3 b. 10-6 c. 10-9 d. 10-12

Quiz 7. The number 2700 MW can be written a. 2.7 TW b. 2.7 GW c. 2.7 kW d. 2.7 mW

Quiz 8. The value 68 kW is equal to a. 6.8 x 104 W b. 68, 000 W c. 0.068 MW d. All of the above

Quiz 9. The sum of 330 mW + 1.5 W is a. 331.5 mW b. 3.35 W c. 1.533 W d. 1.83 W

Quiz 10. Precision is a measurement of a. the total error in a series of measurements b. the consistency of a series of measurements c. both of the above d. none of the above

Quiz Answers: 1. a 2. d 3. b 4. d 5. c 6. d 7. b 8. d 9. d 10. b